The long-term goal of our research is to understand fundamental aspects of ribosome synthesis and function. We propose experiments to study factors and conditions influencing rrn gene expression and specific aspects of ribosome function. Expression will be studied from two different perspectives, the rrn transcription antitermination system, and how the transcription apparatus responds to several conditions that lead to down-regulation of rRNA synthesis. Functional studies will highlight our new rrn deletion strains and are aimed at addressing questions uniquely suited to the use of these strains. In fast growing bacteria how transcription of rRNA genes occurs at increased elongation rates and bypasses terminators is very poorly understood. We will examine antitermination and map out the RNA/protein and protein/protein interactions involved. We propose to examine, using electron microscopy, how rRNA operon transcription responds to conditions requiring drastically reduced levels of operon expression. We will also ask what features of the ribosome guide its response to two specific problems in translation - sticky peptides in the exit channel and switching to tmRNA when stalled. Our ability to produce strains encoding homogenous populations of mutated ribosomes allows us to use these strains to ask where sticky peptides and their effecters interact with the ribosome and what specific features of the ribosome enable it to switch to a tmRNA molecule when a block in further translation is encountered. We have developed an rrn D strain in which we can shut off all synthesis of rRNA. Using this special strain we propose to questions such as: What rules govern the efficiency of mRNA translation when ribosomes are limiting? Are newly synthesized ribosomes required for cells to respond to a cold shock? How stable are ribosomes? The current renaissance of information and studies of the ribosome and translation process put our work into the context of contributing to fundamental information about the cellular translation machinery that apply to all living systems. [unreadable] [unreadable]